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Polymer-metal nanocomposites for functional applications*

Polymer-metal nanocomposites for functional applications* F. Faupel, V. Zaporojtchenko, H. Greve, U. Schürmann, H. Takele, C. Hanisch, V. S. K. Chakravadhanula, A. Kulkarni, … Chair for Multicomponent Materials, CAU, Germany E. Quandt, A. Gerber, Chair for Inorganic Materials, CAU

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Polymer-metal nanocomposites for functional applications*

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  1. Polymer-metal nanocomposites forfunctionalapplications* F. Faupel, V. Zaporojtchenko, H. Greve, U. Schürmann, H. Takele, C. Hanisch, V. S. K. Chakravadhanula, A. Kulkarni, … Chair for Multicomponent Materials, CAU, Germany E. Quandt, A. Gerber,Chair for Inorganic Materials, CAU R. Podschun,Institute for Infection Medicine, University Hospital SH *€: Innovation Foundation Schleswig-Holstein, German Science Foundation (DFG)

  2. Outline • Motivation • Preparation - Evaporation - Sputtering • Examples- Magnetic composites for > 1 GHz - Optical composites - Near percolation composites for sensors - Antibacterial coatings - Nanorods • Summary

  3. Functional nanocomposites Fe-Co-Ni in Teflon-AF • Requirements • Control of particle • filling factor • size • composition • ... Atom << nanoparticle << solid novel properties

  4. Co-evaporation substrate shutter Polymers by evapor. • Polyimide, Polyamide, PU, ...polycondensation of monomers • Teflon AF, FEP, Nylon, ... - thermal decomposition - repolymerization on substrate Advantages • dry, solvent-free • low defect density • high purity • good process control but lower Mw rate monitors metal organic V. Zaporojtchenko et al., Microel. Eng. 50, 465 (2000)

  5. Metal nucleation on polymers a) adsorption b) diffusion c) agglomeration d) desorption e) diffusion into bulk f) coalescence in bulk g) embedding of clusters V. Zaporojtchenko et al., Surface Sci. 532, 300 (2003) Parameters: • substrate temperature • evaporation rates Nucleation also at defects and free radicals!

  6. Filling factor Tailoring the filling factor • Substrate T • Deposition rates Cu in Polyimide Metal volume fraction: Cluster oxidation!

  7. 280 nm Filling Factor < 1 % Composites with Teflon AF Ni • Thermal decomposition • repolymerizationon on substrate A. Biswas et al., Nano Letters 3, 69 (2003) • Advantage: protection of clusters • Problem:poor metal condensation

  8. Condensation (sticking) coefficient C very low for polymers with low surface energy! Thran et al., Phys. Rev. Lett., 82, 1903, (1999) Teflon AF: C ~ 2 ·10-3 C for Ag on some polymers

  9. Tandem evaporation • No oxidation • narrow size distribution • ALLOYS! Fe-Ni-Co clusters in Teflon AF (elevated deposition T) A. Biswas et al., Nano Letters 3, (2003) 69 Patent

  10. Sputter rate [nm/min] (1keV Ar+, dose 1017 cm-2) Chemical yield G(s) (main chain scission) Sputtering of polymers (J. Zekonyte et al., NIM B, 2005) Polymer Teflon AF Nylon 11 PMMA PaMS PMDA-ODA BPA-PC PS PBO PP Cu 25 6 1.3 0.8 0.5 0.3 0.3 0.3 0.3 0.5 2.15 - 6 1.2 - 1.9 0.3 - 1.13 0.02 - 0.1 0.06

  11. PTFE-Ag: strong cross-linking RF (Teflon) and DC (alloy) sputtering XPS C1s Binding energy [eV] U. Schürmann et al., Nanotechnology 16, 1078 (2005)

  12. Magnetic cores for > 1 GHz ρ: resistivity d: feature size  Nanoparticles for GHz • Insulating matrix   “no”eddy currents • Tailoring of alloy without need of high ρ • Orientation of easyaxis by field during annealing or deposition

  13. High frequency permeability 8 x (30 nm FeNiCo / 10 nm Teflon) Quality factor Greve et al. Appl. Phys. Lett. 89, 242501, 2006

  14. Outlook Devices E.g, toroidal microinductor

  15. Optical nanocomposites • Applications • Ultra-thin optical filters • Bragg reflectors, sensors • Magneto-optical systems Ultra-thin color filters Biswas et al., Appl. Phys. Lett 84, 2655 (2004) d <<l • wplasmon tuned by: • nature of metal/alloy • cluster size, shape, separation • dielectric matrix Surface plasmon resonance: charge density oscillation  strong absorption in visible range for nanoparticles of Au, Ag, Cu, ...

  16. Tuning the plasmon resonance frequency Ratio of Au/Ag Au-Ag particles

  17. Electrical properties near percolation PTFE /Au on glass f < fc: insulating f > fc: metallic

  18. Sensor for organic vapors 250 nm Nylon/Au

  19. Selectivity by fingerprinting via solubility

  20. Antibacterial nanocoatingsPartner: Prof. Podschun, Medical Microbiology (110) Growth of Staphylococcus aureus (200)  Ag ions (211) PTFE/Ag 24 h incubation Strong enhancement by Au traces: Zaporojtchenko et al., Nanotechnology 17, 4904 (2006) Sample top down onto inoculated agar plate

  21. Nanorods Rods: d  5 nm, c/a 30! Application: recording > 1 Tb/cm2 ? Fe-Ni-Co rods on Teflon-AF by co-evaporation Greve et al. Appl. Phys. Lett. 88, 063112 (2006) Patent

  22. Summary Nanocomposites:-novel properties: magnetic, optical, electrical, .... Vapor phase deposition:-wide range of d and f, narrow size distrib., alloys Demonstrated: - magnetic materials for GHz - ultra-thin optical filters - selective sensors - antibacterial coatings - nanorods Further information:http://www.tf.uni-kiel.de ff@tf.uni-kiel.de

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